The present invention relates to a method for determining the varnish impregnation state of a core assembly.
When manufacturing a motor, a coil formed by winding a magnet wire with insulating paper is inserted and disposed in a slot of a motor core formed by laminating together electromagnetic steel plates. Next, in a varnish impregnation process, varnish taking the form of a liquid thermosetting resin is dripped onto a coil end portion that forms a part of the coil that projects from an axial end surface of the motor core. Using the capillary action of the varnish, the interior of the slot of the motor core is filled with the varnish. The coil and motor core are then subjected to heating or the like to harden the varnish, and thus the core assembly is manufactured. A method of performing varnish drip-impregnation in this manner is disclosed in Japanese Patent Application Publication No. JP-A-2003-189523.
By filling the slot interior with varnish, the coils are fixed to each other, the coil and insulating paper are fixed to each other, and the insulating paper and motor core are fixed to each other by the varnish. As a result, an insulation coating on the magnet wire is protected from breakage caused by electromagnetic vibration during electrification of the coil and so on. Moreover, the varnish enhances the heat radiation property of the motor core, assists the insulating function, and so on.